Control system



Aug. 14,1945.. k fly.. GE'ss"` 'y 2,381,948 v` CQNTROL sYSrEMy n* *y f rFiled Jan. 29, 1942Y .y 5 shuts-sheet .sv

' IIJKVIEAITC R Lows Glass 'ondvariable and in liirst variable may befshifted atwill. Itis aturi'therjobject of the'invention ,to provide anyir'i-f` v.strum'ent which iriavhave without temporarily,

vvThe 1 1 instruments; Vadapted'fto beused in standing of Vthe.invention,

tratedf and described a preferred Brown assignorimputation'mainmise,1942, seriaiNoAzsnas o y l y v (crisi-+153);f,'.Liriie'presentinventidnfreistes to si: eantrcijsp paratus, and .moreparticularly to` pneumatic the control point-f oi' jone controlinstrumentin response to Vchanges in thevalue oi.'y a control condition.-f-Theinstriiment is also provided with `means wherebythe control vpointmaybe changedk manually aswell as automatically.

contrclinstrumenfts havingprovisicns to adjust kOri/e orf-theobjectsofthe present inventionis Y y to. provide a highly developedpneumatic control .instrumentwhich-hag provisions for manuallyrorraiitom'aticallyr adiustingf the ,control point oi' theinstrument-,or vfor changing the value. at ,l

ywhich the condition ,is being controlled. f

v' Another object'v ofthe invention'is to provide-a controlisystem in.which one variable'under con- {trol mayautomaticallyhave itsvaluechanged sets up an ali-,pressure ythat the iiow. To this"y inresponse toxv'ariationsin. the value` oia'seck1' which. thezero pointyof the its zero'pointfchanged a parti to variations in atf'itmay'beusedftc vary thefvaiue of theiiowly with para vpart or thisspecification. For al betterunderhowever, yits advantages andspecinceinem obtained vwithin: y -rei'erenceshould belhad tothe ,Y l

1 drawings and descriptive matter in which is ilius if :embodiment ofii' `pressure transmitinstrilint which/is adapted to 'setuppressurefproportional tothe flow through a conm. '3 is a partici rearkview of' meetinstrument shown in Fig. 2.V f f Y yii.rtiiiciallyupsetting the y control'ofasyster'n cit/.which the instrument is whichiste have secoinnanyins of my control system'are the'control-oithev'alueofl any-condition 'such as temperature, pressure or y,-moisture-or anyfother condition vitsvalue controlled in response thevalue-ora'nothercondition. Bylwaof vex- "ample, however, theinventiomwill befdescribed kjea'ci'i side ofl which pressure tend' totheinstrument 1. It

keine i by the instrument "of the flow through the 'pipe Fig. 4 isafsectional view oi apilotva-lve used intheinstrur'nentof\l"ii.`2.` yFi'g.f5"is a view takenon lines 5-5` of Fig. 2. Fig. 6 isaview vpartlybr ken away showing the control instrument with itsV control pointadjusting mechanism and. I "Fig. 7 is a. viflw taken on lines 1'1"ofFig.6." vReferring first to'Fig. 1. there is shoWn'a'pipe `Ith'rughjwhich a iiuidfis "flowing, The dow through the-pipe is measuredby a iiowmeter 2 ofthediil'erential pressure type which in turn isproportional f Vto end, the pipe vi is provided with an oriiice '3from'l each side' ofwhich pressuretaps l and l extend to the instrument.

In a fsixnilarfmanner, ilowvth'rough a pipe 6,

Avthat is tobe 'controlled in accordance withk the tisaccordingiypryidedwiin an ermee; from taps) and i0 exris noted that ktheinstrument] is rdisclosed asV being'a recording i instrument while heinstrument 1 isdisclosedfas being an indicating instrument.' nachinstrument has exactly'the same measuringand pressure pro-v ducinginstrumentalities and veither may be made indicating or'. .recording aszdes'ired. In the systemdisclosed a record is made'of, the ilow through2 and a recordis made I lbyan instrument' Il. that also servesto controlthe iiowhthrough .the pipe i in a manner to be described.

The instruments 2 and 1 are-adapted 'to set up lan air pressureproportional to the lnow in pipes I and l respectively by means ofmeasuringy and transmitting instnimentalities disclosed in Figures!to'5. instrument lwillbe'jdescribed indem y Attached to the back oftheinstrument 2 by means of a .bracket l2 is a U-tube manometer i3 havinglegs I4 and Il that are connected respeci til/ely t0 l `are Joined by a451 'neunn, 'such the W in pipe" the pressure" transl` and ILl The legscrosstube Il'ftok form, with the im. fa passage v Y I changes thekpressure on opposite sides of' the ,orice will'change'andwill cause thelveloffthe measuringfliquid in a'iioat chamser formed linici: a float i.on the Il to rise or fall. As this occurs surface of the liquid l1 acts"throughs i'ever'll to rotatefa shaft 20 to a position corresponding tothe Rotation of :the shaft and value o! the ilow, 2l acts on pneumatic apilot valve to set up an air in whichfa suitable measuring asmercury,inay be placed. AAs, f

tivol part lever. by a nnku so otally mounted on the shaft 2,0. A spring2l between `the ears holds them apart an' amount that may be varied by ascrew Il'rwhichfextendsv through theear Il and is threaded vinto the ear22.' In this manner thel rotation of shaft 2l yis imparted to lever 2l.Through l link 21 that is l attached to lever 24 and suitableconnections V(not shown) the rotation of shaft 2l moves a pen arm asumetainer Il that is attached to the casing Il;l `The inner wall oi' 'thechamber is formed by a flexible bellows I'I, thereby making the chambervariable in size. Fastened to the interior of the bellows and projectingdownwardly toward the casing 5I is an exhaust port I8 that movesupwardly or downwardly `as the bellows 51 is collapsed or expanded :bychanges in pressure in the` chamber. A second bellows 59 forms, with therst bellows, an interbellows space whichl is connected by suitable portswith'the atmosphere.

The lower end of the movable exhaust port t@ extends into a chamber ilthat is connected with the. above mentioned' eways by means of an intakeport 0I. The intake port tl and .the

. exhaustport il are adapted to be closed by a 2l across a chart Iltomake a'record of thevalue '1 of the flow through the pipe I. The chart2i is rotated by a suitable clock mechanism at anyy desired speed, suchas one revolution per day.'

Rotation of shaft also operates'a pressure transmitting unit 30that,vwith a Ipilot valve SI shown in detail in liig..4,- serves `tosupply an air pressure varying with thel flow to the recordingandcontrol instrument .I I. The unit MI. consists of ,a support ,32 thatis suitably fastened vin `the instrument casing andwhich has attachedfto it valve which ispivoted in the casing and which is biased in adirection to close both ports by any Vsuitable means. Chamber 20 'lnection $6.1

a cup shaped casing I3 and la. bellows ll .that form i between them anvexpansible chamber-1Lk The bellows is kept in a, normally expandedposition by means of a springfthatfrests withits lower end'against anabutmentjl. attachedto the bellows end wall and-with its upper `undbearingr againstthe lower surface of support l2 and sur,`

`roundlngan opening formed in support; .The

amountthat the bellows 34 can collapse is relulated bythe engagement ofits end wall with the lower-end of ya sleeve .thatis alsqattached toltllesupport I2.

l 'As' thebellowsv .changes-in' length due changes in chamber a rod 38will be'lnoved rod has its lower end resting up and down. This inasocket formed in abutment I'Iand hasits upper end adjustably pivoted at4l to a bell crank lever 4I that is in turn pivoted atliseelilg. 5)

plies air tothe to the supporter.4 .Attaohedto a shaft Jour.

nailed in the otherfarm` ot the bell-crank Il "is a whichhas'one vendconnected anarlny H lllgtormed on'the lever 24. Thebellcrank .4|

is norlnally'biasecl byy a light spring um ojolochwise dlreouonln Figure2 morder tokeep .tnelower end of rod u against the abutment l1. 4

Pressure in the chamberll is controlled by the movement of a' dappervalve"v relative to a bleed nozzle 4l that is mounted on` the supportn."Tile dapper valvel is pivoted toaproiection` 4l on the support `and isnormallyk biased 4by gravity and/orr a spring toward the nozzle. `Theflapper may be moved awayfrom the nomia by meansof a pin that extendsfrom the upper endo! ythe, leverMm y Y The pilot valve li which hasbeenreferredto above is located in the lower left kend corner'oi' .theinstrument casing asshown by dotted linesin Fig-,2. I'his.pilot valvevisdisclosecl in'detail in Fig. 4 and consists oraoaslng that has sulla"able passages formed infit. One of these passages will direct air. thatis supplied to the ,pilot valve through a small illter I2 and lailxedrestriction Il to -a pipe Il that lslconnected with the bleednozzle n. or the transmitting umt as. The vair which ows through the`restriction I3 also is in communication with a chamber l5. The outerwall ot this chamber is .formed by a coni. 2.150 Stop the lm n the pilotl ber. Il ilvetimes surein chamber `move toward the creasein .pressureAir; is supplied to thevtransmitter. unit 1I and the pilot valv'ell at asuitably regulated pressure `through apipe Il, thepressure inwhich isindicated byv a pressure gauge Il. Connecting the pipell and the pilotvalve is a pipe 8l that suppassageways' of the pilotcvalve. v Initheoperation ofJ 'this'.instrument. as the shafty 2l is rotated duetochanges'in now kthe dapper 41 is moved relative to the nozzle (48 tovary the escape of ample. the ilow. through pipe I increases .the floatIl 4will be lowered in Fig. 3 causing thev shaft 2e rotate clockwise`inthat figure and counterclockwise in Fig. 2. Such a rotation of theshaft `2l will act through the levers 2 I and 24 and arm to move.-the'jlink I! upwardly to rotate lever `Il in al counterclockwisedirection. vAl; the lever rotates in a counterclockwisev direction thepin Se attached to it will permit the valve 41 to nozzle le yto stop theescape of air through the nozzle. This will produce an inin the; chamberIl causing.

downwardly its lower endwill-y engage the valve exhaust of air throughthis port and will move the valve clockwise to open the port r 8|vsotllatair. can now into the chamber' 80 and increase the pressure inthat chamber. This increase in pressurey acts on the interior of bellowst! toexpand that bellows and bellows 51, movins port Il upwardly. Whenthe pressure in Y chamber. III `has been increasedjenough to balthe y uincrease in-pressure lin chamber .the Dort` il .wlllbe closed.Normallythe area ofzbellsabout five umesltnatof. bellows al so .thatAin; chamber 55. -The pres- II .isslso transmitted through a pipe to thechamber Il in theunit Il causing o collapse ofthe bellows u or. umtunltagainst theforce of springy Il. Asthe bellows col-I lapses rod will bemoved upwardly Ito rotate bell crank 4I vcountercloclswise around itspivot 42. Asthe bell crankV II moves it .will movethe pivot shaft 4l 'sothat pin SII on thesupperjend of lever il will tend to move dapper 41away from air through this nome and. thereforer the pressure in chamberl5. It, for ex- .valve produces a pressure in c Y mow' valve' luhtedproduceva pressurA change .jtrhexheilst v i has 'set up will bemaintained, Pressureis 'P'iltffllfMilchv l Pipe ll .and www inv emmersimllrtoi-the l instrument 1 tojproducejan increase impressum? l creasethe pressure intpipejl asaQresultcf a v "f The 'pressures' Vinpipesjllyfandfl'i are applied component partsof theinstrument Ilwhichisdisclosed'indetail in Flsfs v membernlllthat has one arm 1,03extending to respectively jto thev 'at their apenL ep f e riveted 'on.the suppot "1s: lAlsoiiittach'ea assises 'chandelle in cfollcw-upniovernsnt. the

original chance in now. y:it that'the pivot point I llj'on the.Dper'endof rod lljcanb'elmoved to the leftfor -to the"right{ inorderj'tofchanse" the leveryarm of nrroftmnhl to. msnm se. .ustedthe'bell `c rankjll; andf'thereforerthejamount ofl follow-unibet f thatnormallythe b obtained.; "It B150 noted ran amount sumcientfto in thesystem that isA valve'c in the pilot valveunit pressure inthe chambery12 yvaries f :Mvement 1am It are aanname by anni: n

permit expansionr ofthe be movedfaci'responding'ly amountacrossitheoflthe shaft l'I-*alsoserves'lto opferate apneumatlccontrofinstrument 'whichacts vtr set upair pressures varying"in accordance with simwteneouslv closes '120th theintak Dort and mythatY` ed inthe system as sresul tfojf 'acharne` inflow whichproducesmovementl of 'the flapper valve* vll'l and eonseqiientlyl exhaust portIl ma 'direction to open'tne poi-t u orina direction' f dto' opentheport It: ,1t-wm bebbvius the Y above description thatV av 'reduction' innow vthrough the pipe] will result `in arcduction in contains that are'identical -tls/those in Eig.

Zexceptethat norecord yisuia'eleby this'instrumentfoi they flow thrcughvthe pipe v6; vInstrument l der 'pressure through a 1 is :supplied 'withair f.

ai'v well'fheconnectedr` with the in theflowinim A and; '1,Y Thisinstrument Will-OW- be described.

Thefpress cofv the airsetiup'bY-the *instru* thro( mutue-pipe 1| temevapen and' to .the variation inthe' flowfin` pipe' 6to vbeapplied rLocatedinfthe instrument il is mancanti-c1' vniechan'islr'i thatserves-to vary the press'uieof a supplyof'airas thelilowthroushfthepil'ie-Ivai'ies.V .j

yl'iiechanisiii consists of an air controlled unit v Il and a pilotvalve"'unit 02 that may take the e formofthe commercially availableBrownAir-O'- Line controller which is fully disclosedjin Pat- 'pressureof -whichmay be measured by-a'gauge Il. The air then passes to'thepilotvalve'll.

Air is supplied-by the 'control mechanism atresli-y 'f lated pressuresthrough apipe'" toa 'diaphragm lpperatega-ccntrolmechanism which-islocated ln toanex'pansible chamber 12in Yhand*f tir'iierof Vinstrument,'Il

Y toalsiilliwrt 1I which Increasein the pressure pipe .1 iby theinstrument] tofcollapse the bellows 1I -f of leverfili and. at its lowerend to a leve'rulll.

The lever l is pivoted at llt v'anti has apinl Il Bum of a spring 1.6L-

collapsing movement is bellows. The .right of pivoted at by a cupkshaped casingv `14, bothoffwnichyaref" line axiallyfof andfbehindthepivot Ill.- As the chamber fin-the valve 90; The pressure of the:ilitothe valveis measured/by, Pressure sauce eontrormt is perstedsymov'emntofis ilapperfvalvellrelative to ableednozzleil in g a'mannerfullylfdescribed in the above mentioned patent.v Movement is `impartedto the ilapper 98 `in accordance. with movement ofrthe pen II rbyvmeansfo'f'al lever system. This lsystem is supfastened intheinstrumentjcasins. l'ivoted to the back of Vthisplate yat l10| isa-mtiltiple armed Y Vend oit which-fis ysupported by `the lower end of alinkv |08. T'he upper endv oflink |08 is pivoted,`

tothe outerend oi an arm |01 that isfastened.

along with lpenhrm I6 and arm 88, to the shaft 81 for movementtherewith.lThe iloatinglever IIII' is so shaped that itsgcenter point fallsinafloatingy lever |05: This, in tum, imparts movement tothe flapperi ybymeans of a link Ill shaft cz, me; movable j-.with this "shaft is a leverx the lever Il and the rcd 1 8 amnestie, Y

c, a chart 'It' tomake a" ccrd of the value' ofthe ,'tlowfthruah pipe; L:Theypen is lattachedto* a `rherlfto itganl projecting downwardly imv'llltofa levrllij tn ashaft I2 that is tothe "pipell ameans is providedmean! lof a v flexible tube I Il Qpointsettins. unit In.:

that isipivoted at its upperv end to the-midpoint that acts to movethedapper, away lfremthe noasle against a.- n'atural .bias toward the-noz-V each position of the pivot lIIN a `certain pressureinchamber 'l2vwill cause acertain pres- Y sure; to .be produced 4bythe L'controlmechanism. .There'fore, inf:l order toychan'ge the pressure .in "pipeIllfor a givenpressure in chamber :l2v or` to change'the value at whichthe instrument will maintain Athe flowinpipe. 6 some means must beprovided tovraise and-lowerthe-pivotpoint i,

Since it isdesired tovari' e ljin'laccordance with the' variations yinwhich will adjust pivot point cillin accordance with variations inpressurevinpipe Il: ',1

YTo this: enegithefpise Aun extended 'intoytiie 1 r"interior'iofilzlstr-ument' I'lvand'is connectedfby with ra remote control jto'ajdiapnrazm valve se thats mated -m the Y resiliency ofthe bellowsandthe force of. a spring Y to a limit that is determined by the end ofa tubular stop |2I. As the bellows expandyand contract a bellows rod |22that hasits lower end in a socket I28,fattached to the bellows end'wall,will `be moved axially. The upper end ofthe rod |2215adjustably*attached` at |24 to a lever |25 whichis in turnattached to apivoted shaft |25. This shaft iscoaxial with the. shaft II5. `Alsoattached to 4theshai't |26 is a lever arm I21 that inV turn` hasia leverarm |28 pivoted toit at |28. 'I'he Varm ;|21 is provided with anup-turned end |80 aginst whichthe arm |28 ,is normally held by-a spring|8I. vThus the threearms in Veffect form a bell-crank lever and turn asa. unit around the axisxof shaft |26 as the pressureinchamberllfchanges.` 'I'he assembly of leversis normally biased in ,a clockwisedirection by a spring |82 to keep the lower end of rod |22 inengagementwith the `socket |28. f l, v,

Movement of the bellowsp||1fin `response to pressure changes transmitted`by instrument 2 is used to rotate the member l|02 toraise and lowerpivot |04` and therebyfadjust the control point of instrument I I.'I'his isaccomplished by means of a link |88 whichis pivoted at itslower end to the outer endof lever |28 and vat itsupper end.to aprojection or arm |84 on the member |02. 4Inordecrto indicate the valueat whichrthe ilcw'in pipe 5 is being maintained themember |02 is alsoprovided with a -downwardly extending index member |85. The lower vendo! the index cooperates with graduations on the chart 80 to indicate howthe flowis'being-,controlledz In'some cases it may be desirable to limitthe ilow inpipe 8 to some maximum or minimum value regardless' of whatthe flow in pipe Imay be; For this reason adjustable stops |86v and |81are provided to limit the rotative movement of member |02; These stopsare, pivoted-one in front of the .other at IOIgon the plate |00.`

Whereas the member |02 is on the back of the plate |00,-the stops|86 and|81 are on. the `front of the plate and their left ends cooperate with ascale |88 to indicate their positions. Member |02 is providedwithanabutment |89 which extends through a suitableopening in thegplate |00intoa plane in whichit will engage one or the otherofthe stops asmemberI02 reaches the limit of its travel. y x

If the pressure in chamber to such an extentl that the member |02 wouldbe rotated counterclockwise more thanenough to bring abutment |89 intoengagement with stop |81, spring |8I will' give toapermit separationoflever |28*from the turned up edge |80 of lever |21. The over-travelbetween partsV |21wand `|28 will be-suilicient to permitany amount ofcontraction-of-bellows |I1 that'can takeplace.` If, onfthe other hand,pressurein chamberl |I0 should be `reduced to such an amount that abutcment I89on lever |02 will move into engagement with stop |80 theover-travel that will occur after this happenswill merely move abutment|28, fasl i asume f `support member II4 that is pivotally mounted on itened tothe end wall ot the bellows, away from the lower end ofv rod I22. The socket in abutment |28 which engages the lower end of the rod I22 is4 deep enough so that `any desired or necessary over--travel may beobtained without the socket movingcompletely away from the rod. Theconnection between rod |22 and arm |25 is such that the' upper end' ofthe rod may be adjusted to di'erent distances from Vthe pivot point of'the'arm. To this end the arm |25 is provided with anV uptumed edge |41into which an adjusting vscrew |48 is threaded. As the -adjusting screwis rotated the pivot |24 of rodA |22 is moved along a slot |48 in arm`|25. This adjustment `produces a change in the eifective length yoi' arm|25 and therefore a. diierent amount of movement of the pivot point |04for a'given pressure change, in the chamber I|8. Stated in other words,the control point of the instrument IjI is changeddinerent amounts for agiven change in the'iiow in pipe I. An indicator may be provided, ifdesired, to indicate the point ofladjustment of the rod |22 along arm|25. Itfis to be noted that a similar type of connection is shownbetween rod 18and lever 8| in the pen adjusting unit located in theupper left corner of the instrument.

The manual means which has been mentioned above `for adjusting thecontrol point of the instrument independently of any pressure changethat may ,take in `chamber -||8 is operated by means'cf an arm |40formed on the bracket II4 which supports the unit I I8. Pivoted to theouter end oi' arm |40 is a rod I4I whose upper end is threaded and isireceived in threaded engagement with a beveled gear |42. The gear |42rests in abearing that iis formed ina bracket |48 which is in turn`suitably attached to the instrument casing, or to ltaub-plate which maybe located inthis casing.V As `the gear |42 is rotated it will move rodi|4I upwardly or will permit this rod to movedownwardly under the forceof a spring |41 which normallybiases unit II8 in a clockwise directionin-Flgure 6. The gear |42 is rotated `by means of another beveled gear|44 that is in mesh therewith., The lbeveled gear |44 is attached `toashai't |45 which is joumalled for rotation inthe front part of bracket|48, as best seen in Fis.- 7. A knob |44 is attached to the v'from ofshan u whereby the shaft maybe easily'rotated when necessary.

The amount of adjustment that is provided is suillcient so that -if yamaximum pressure is in chamber lllthereby moving the index |85 to itsvfull scale position, the knob can be rotated suiiiciently to move unit|I8 in a clockwise direction far enough to bring the index pointer tofits zero position. Conversely, if there is a minimum 4pressure in thechamber ||8 and the index v| is, therefore, at its zero position on thechart,

the knob |40 may be rotated enough to bring the index |85 to a 100%position on the chart. Such an adjustment permits a so called zero shiftoi' the index with respectto any pressure that maybe appliedin thechamber ||8 as a result of V,changes inflow in lthe pipe j 'I'heoperation of the` instrument should be clear from the rabove detaileddescription, but a summary will now bel given with the assumption thatit is desired tov control the flow through pipe 0 to some :given valuewhich may be adv.illsted in accordance with variations in the flowthrough pipe I. `In the normal operation as the tiow through pipe 0varies, the instrument 1 will. set up varying pressures through pipe 1|assigns t pendedclairns; `and thatin some cases certain yto'befappnedtoehember 12 whichin tumnioves* t 'features of'thisinventionmay sometimes be used thevpenf85 across the char-t and'` operates'theanormal 'valu'eu Conversely if the flow through pipe 6 decreases thepressure in pipe ,6B will be decreased to2 permit thevalve to open andincontrolunits 9| andu92. vAs these units areopery 5 'ated varyingpressureswill be applied through pipeY 95 toy the diaphragm chamber 9 6of valve y` 90.., If.the lflow increases 'throughpipe ylan increaselinpressure will be applied infpipe 6l toclosethe valve and rreduce theflowftov 'its 'fcrease'the ilow to its normal value. In view of yfthefact that some desired lratio is te lbe maintained between the rflott'in pipes I 'and 6 a means is vprovided to shiftthe control point of theinstrument rI I as theflowkinpipefl. varies." ATherefore, the instrument2 sets up a pressurein pipe 64 which'is'proportional tothe flow in pipeI.. 1

.This pressure is 'applied'to the unit '-I I3 to shift theright handend.l of. floating lever. |05 and thereby operate the control'unit y9i.and 92 to:l

' the'pressure-inpipe'andthe flow.l through *pipe das" the fiowthroughpipe l changes. o

t; j If it is desiredto .inoreaseor `decreasel the j amount of rfi'owthrough vone pipe'ior a given flow through the Aother the knob.v I46'mayberotated l toA bodily shift thefunit I I3. around its 'supporting`shaft H5. -Ifr there vhadbeen a minimum.

" pressure in chamber' iisindieating that no, fluid v was flowingthrough pipe I,norm'ally the index Y lafwould .be over thei zero pointonthe'chart t f throughpipe I withv respect .to'tha't through pipe 'zS'the-upper'endfof rod, |22 maybe moved'toward y "or .away fromtheful'cr'um `point`l26 `of thearm |25.Vr v Suchlan vadjustment willVprovidemore or; less movement of the index Il! for a'givenpresnow-through pipe t.y r

f 86 .to .stop theiiow through rpipe6. `With an :adjustment-"of the typevprovide'dby the bodily Y.

- y movement'oi unit |I3'theeontrolinstrument may fl "be-ma'defto supplya..ce1 tainI amount "of gfluid f throughpipeuli when-thereis no flow inpipe I i "byrotating' unit Il 3 lin one ldirection or .may .bev

f made toprevent any iiowthrough pipe f 6 until there is somepredeterminedA flow in pipe I by4 rotating unit I I3v Vinthe oppositedirection. Thus' the. effective. z'ero point of: the instrument isVVvgfs'liifted by yrotationiiofirnob |46. This adjustment-maybelmad'e'gwhileythe controlsystem is inf operation fwithout `upsettingVthe system.

`- If itis-desiredv to vafythe'ratidor the now change in'chamber H8. Iithe rodl |22 is in one--poosition-the leveragebetweenfA-.this rodandflinki may be suchfthat for two unitsof 'i'llowo through pipe.r `Ithere" will `.betwok units through pipe 6; By'changing'the position o irod s |22 on arm |725 .two units of flow through 'pipe I1 maybe obtained.for three units or oneunit of While inaccorda'nce withY the'provisionsof thestatutes; Iihave illustrated and described the y bestform.v of this invention now Aknown tolme,

it would bey apparent r to those. skilled in. the art y that changes maybe vmade intheform of the apparatusdisclosed vwithout departing from theclaiml as new isf cluding an expansible chamber having a movable walladapted to be moved by changes in pressure applied thereto .and attachedto said supto advantage'without a `corresponding use of j `otherfeatures.

Having new described this invention, what I desireV vto secure byLetters Patent is:

, t l.v In a measuring and'controlinstrument havi Y ing a casing andvachart upon which a record; 'l0

of the value of a condition may be made. ya control unit operative toset up a control impulse to control the value of -a variable condition,conc trol point adjusting mechanism for said unit located behind thechart, said mechanism being t 4mounted on a support, means to pivotallymount r said support inthegcasing, said mechanism inport, connectinglevers extending betweensaid control unit andsaid movable wallconstructed `and arrangedgso that-*the latter can adjust the formerfmeans to' adjust the connectionvbetween said levers to' vary the amountof movement of said levers for a given movement of said `wall, l 'saidsupport including an arml extending away from Aits pivot, a rod'pivotally attached`A to said 1 arm and vextending 4in the'casing to aApoint beyond the edge of the chart, and manually operable means actingon the extending end of 'said Y rod to shift the same whereby saidsupport will be adjusted aroundits pivot to change the position of saidlevers.

fj2.-In a control instrument having a control"k yunittvith an adjustablecontrol point and being system' moved bysaid expansible wall tor adjust'the control pointk of ksaid unit, Van varm `attachedV @l to said supportcoaxial with-its pivot and extendl y ins away -from the same, and meansto move .the

outer end ofk said 'arml tothereby rotate said support aroundk its pivotto adjust said lever system.

3. In a controlv instrument having a controlv 'unit with an adjustablecontrol 'point andbeing mounted in a casing, control point` adjustingmeans fory said unit mounted in said cas f n.18 including a supportpivotallymounted-in said casing, parts forming an ."expansible chambera-connection between saidv wall and leversystem to permitf movementofthe latterfas. said wall moves,l means tovary the p ointoof engagementbetween said leverv system and. said' connection,

and means tobodily moveA saidy support around' its pivot lto adjustsaidlever system.f

LoUIs GEss. n n

